We have found that the L-system of amino acid transport is nearly absent in chronic lymphocytic leukemia (CLL) lymphocytes when compared to blood lymphocyte (T-enriched) or tonsillar lymphocytes (B-enriched). We propose initially to further define this defect in transport by comparing explicitly the kinetic parameters of the L-system of CLL cells to normal human blood B lymphocytes. We will examine also the effect of stimulation with B-cell mitogens on the kinetic parameters of L-system uptake. In particular, we will determine if a rudimentary L-system of amino acid transport can be activated by new RNA and protein synthesis under conditions leading to mitogenesis. Our preliminary data indicate that the L-system in CLL cells has a profoundly decreased maximal velocity of transport (one-tenth that of blood or tonsillar lymphocytes) for the L-system of amino acid transport. We propose to characterize the membrane proteins associated with the L-system in normal B lymphocytes using photoreactive radiolabeled amino acids and other photoreactive probes in conjunction with protein separation techniques. We then will determine if these proteins are reduced or absent in the membranes of CLL lymphocytes. These studies propose to compare the amino acid transport systems both physiologically and biochemically in CLL and normal B lymphocytes to define the specific abnormality in L-system transport that we have discovered to be present in leukemic lymphocytes.